1. Field of the Invention
The present invention relates to data modulation, and more particularly, to a data modulation method capable of suppressing a DC component using parity information of a synchronization codeword, and an apparatus for executing the method.
2. Description of the Related Art
A multimode coding method is a method of granting DC suppression ability to a modulation code without DC suppression ability. Even though a-bit additional information is inserted in an input data row, 2a different random data rows are generated, and modulation without DC suppression ability is performed for the 2a different random data rows, the multimode coding method has DC suppression ability by selecting the modulated data row having the smallest DC component among the 2a different random data rows.
In a conventional multiplexing method of converting an input data row into 2a different random data rows by using the a-bit additional information, input data is transmitted as a run length limited (RLL) stream by consecutively scrambling the input data. However, if an error is generated in the transmitted RLL stream when inverse data conversion is performed, the error propagates, affecting not only the data where the error was generated but subsequent data as well. Such error propagation is characteristic of a multimode coding method using scrambling.
Further, in the conventional art, in a case where additional bits for a synchronization codeword and a multiplexing ID are inserted in a data row multiplexed and randomized through consecutive scrambling, or where the multiplexing ID is inserted in the data row according to a size of a data block, regardless of the synchronization codeword, a number of additional bits corresponding to the multiplexing ID increases.